Avoided closing the database connection within a transaction.

Refs #9437.

django/contrib/gis/db/backends/postgis/operations.py

@@ -402,18 +402,10 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
         """
         Helper routine for calling PostGIS functions and returning their result.
         """
-        cursor = self.connection._cursor()
-        try:
-            try:
-                cursor.execute('SELECT %s()' % func)
-                row = cursor.fetchone()
-            except:
-                # Responsibility of callers to perform error handling.
-                raise
-        finally:
         # Close out the connection.  See #9437.
-            self.connection.close()
-        return row[0]
+        with self.connection.temporary_connection() as cursor:
+            cursor.execute('SELECT %s()' % func)
+            return cursor.fetchone()[0]
 
     def postgis_geos_version(self):
         "Returns the version of the GEOS library used with PostGIS."

django/db/backends/__init__.py

@@ -472,11 +472,13 @@ class BaseDatabaseWrapper(object):
         Context manager that ensures that a connection is established, and
         if it opened one, closes it to avoid leaving a dangling connection.
         This is useful for operations outside of the request-response cycle.
+
+        Provides a cursor: with self.temporary_connection() as cursor: ...
         """
         must_close = self.connection is None
         cursor = self.cursor()
         try:
-            yield
+            yield cursor
         finally:
             cursor.close()
             if must_close: